Add hide Magisk Manager feature

unhide/src/main/AndroidManifest.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.topjohnwu.unhide">
+
+    <application
+        android:icon="@mipmap/ic_launcher"
+        android:label="Unhide Magisk Manager"
+        android:theme="@android:style/Theme.NoDisplay">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

unhide/src/main/java/com/topjohnwu/unhide/MainActivity.java

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+package com.topjohnwu.unhide;
+
+import android.app.Activity;
+import android.os.Bundle;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Locale;
+
+public class MainActivity extends Activity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        String command = String.format(
+                "pm unhide com.topjohnwu.magisk\n" +
+                "am start -n com.topjohnwu.magisk/.SplashActivity\n" +
+                "pm uninstall %s\n" +
+                "exit\n",
+                getApplicationInfo().packageName);
+        Process process;
+        try {
+            process = Runtime.getRuntime().exec("su");
+            OutputStream in = process.getOutputStream();
+            in.write(command.getBytes("UTF-8"));
+            in.flush();
+            process.waitFor();
+        } catch (IOException | InterruptedException e) {
+            e.printStackTrace();
+        }
+        finish();
+    }
+}